As promised in last week’s Hunter-Gatherer Fitness post[7], I’m stirring up the (apparently much awaited) subject of sex – specifically the benefits for physical and mental well-being. Uh, you mean coitus? Yup. Thanks to everyone who responded to the announcement with rousing enthusiasm as well as comments and questions.

What could be more Primal than sex, many of you have suggested. Absolutely right. It was probably one of Grok[8]’s most valued pleasures. (Are people today much different?) For our part, however, we have new freedoms in a manner of speaking. Although we might honor the evolutionary imperative behind our primal appetites with eventual procreation, we’re not beholden to the natural odds with every tryst. As I’ve said many a time, I love studying and learning from the example of Grok and his kin. Nonetheless, I’m a happily modern man in this instance as much as any.

I’m not just talking hedonistic indulgence here (not that there’s anything wrong with that). There are genuine health benefits to be garnered after all. Today I’m after those copious “ancillary” benefits of bonk – the gratifying (albeit overshadowed) enhancements to our physical and mental health that come from the physical exertion itself as well as the biochemical cascade of everything from estrogen to testosterone, prolactin to oxytocin to beta-endorphins.

Before we proceed, let me offer the expected and requisite Primal caveat: I’m talking here about safe sex ideally with a committed partner. What good does it do to blow the overall health benefit by putting yourself at risk for the myriad of sexually transmitted diseases. Likewise, why negate the mental health boost by pursing sex in a relationship/liaison that isn’t emotionally healthy? ‘Nuff said?

Now for those long awaited advantages…. Let’s cut to the chase here, get to it, and jump right in. After all, there’s much to discuss and disseminate today. Lot of ins, lot of outs. (All right, I’ve had my fun….)

1. Improve Your Stress Response – And Your Blood Pressure

Sex certainly has the power to take the edge off. (Stress just kind of slides off….) The process of arousal and orgasm, of course, let loose a mesmeric elixir of natural pain killers and relaxers. What’s not to love? Though sex generally offers the most intense dose of aforementioned chemical cocktail, caresses of all kinds can impart generous benefits. (All the more reason to take your time and relish the full experience, I’d say.) Research has shown that a partner’s touch[9] – whether curling up under the sheets or simply passing in the hall – initiates the release of oxytocin, which in turn can lower blood pressure and heart rate[10]. The effect goes for so-called cardiovascular reactivity, the response of the cardiovascular system to stress. Participants who received comforting touch from their spouses before stressful events displayed lower blood pressure and lower heart rates[11]. If that’s what a simple hug can do, imagine the inspiration you can give your partner the morning of a big presentation?

2. (While You’re At It…) Cut Your Risk for Cardiac-related Death

On a more dramatic note, the unique closeness of sex can have more consequential impact in the cardiovascular realm.In a 20-year long cohort study[12], researchers followed more than 900 men and found that having sex twice or more a week decreased a subject’s risk for a fatal heart attack – by more than 50%. That’s nothing to shake a stick at.

3. Upgrade Your Immune Function

An often cited study[13] from Wilkes University suggests regular sex might offer a surge of immune potency. Among the 112 surveyed students, those who had sex 1-2 times a week showed a rousing 30 percent boost in salivary immunoglobulin. Those who had sex less frequently than once a week had a slight IgA edge over total abstainers. (In an interesting wrinkle, the “three or more times a week” crowd showed slightly lower IgA levels. To their possible chagrin, the researchers didn’t ask participants about the number of partners or other potential “relationship” factors that might have influenced the findings. Hmmm…lack of sleep[14]?) Although it’s a study to take with a grain of salt, the basic premise is probably sound. As welcome as it is, the usual exchange of fluids (or the body’s anticipated exchange) represents contact with a foreign substance that likely contains some kind of microbial profile.

4. Get Some Pain Relief

Anyone who’s gotten jiggy with it when they’re sick knows sex can offer a temporary respite from their symptoms – especially when it comes to pain. (Kind of turns the proverbial headache excuse on its ear.) Both arousal and orgasm trigger the production of oxytocin, which then initiates a sensational rush of endorphins and corticosteroids – both fairly potent pain killers. Post coital bliss indeed.

In a study[15] published in the Bulletin of Experimental Biology and Medicine, subjects who were given a dose of oxytocin saw their pain thresholds balloon by more than 50% during the course of the experiment. Seriously, who needs Advil for an analgesic?

5. Steady Your Cycle – and Possibly Increase Your Fertility

Physicians prescribe the birth control pill left and right to women who have irregular menstrual cycles. Regular sex might present a more enjoyable alternative for that particular purpose. Women who have sex with male partners once a week or more, research has shown, are more likely to experience consistent menstrual cycles and (as a result) have fewer fertility problems than women who had sex less often or abstained entirely. One possible reason? Male pheromones[16]. Researchers from the Monell Chemical Senses Center and the University of Pennsylvania School of Medicine honed in on the pheromone link by applying men’s underarm secretions obtained to the upper lips of women subjects. (The image itself is kind of mood killer.) Whether absorbed or inhaled, the magic mix of aromatics in the male samples caused the women’s cycles to normalize toward a consistent 29 ½ day cycle.

Frequent sex with the same partner over several months or more can also “prime” a woman’s body for a healthy, full term pregnancy. Research at the University of Adelaide in South Australia showed[17] that women who engaged in frequent sexual activity with their committed partners (including oral sex, which actually appeared more effective in the study[18]) had higher rates of conception and fewer incidences of miscarriage, preeclampsia, and high blood pressure. Women’s bodies, the researchers suggest, literally learn and come to accept the particular proteins of their partners’ semen in a process called immune modulation. Having become accustomed to the familiar semen profile (oh, you again), the woman’s body is less likely to reject the fetus and placenta that result from conception with that partner.

6. Reduce Your Risk for Prostate Cancer

Research has linked frequent ejaculations (yes, the solo gig counts here) with a slightly lower risk for prostate cancer in later life[19]. The golden frequency in this study? Twenty-one times per month. It’s a tall order, but I know you can do it.

One possible explanation for the decrease is the “flushing” theory. In its efforts to concentrate minerals and other necessary substances from the blood to make semen, the prostate can end up collecting a concentration of toxins as well. Releasing the semen – with said toxins – flushes the system of said impurities. (Gives a new meaning to cleaning out the pipes.)

7. Look Better

Now we’re getting to the good stuff. (Kidding.) Yes, there’s the ever flattering afterglow. It’s a shame they can’t bottle that. There’s so much more to gain, however, or maybe lose. How about calories for instance? Estimates vary but average around 85-100 calories per half an hour. Of course, real life expenditures diverge depending on how zesty an enterprise you enjoy. In terms of calories burned, you’re looking at low to moderate level activity, but your heart rate can easily climb to high intensity levels. It’s probably the most enjoyable cardio you’ll pursue any day of the week.

Then there’s the workout itself – a toning and stretching and strengthening that includes muscles you didn’t even know you had – ala that next morning ache. (Don’t forget about those less obvious – and all important – pelvic floor muscles, which support everything from orgasm intensity to urinary continence.) On the chemical front, intercourse offers a boost in testosterone for stronger bones and muscles. Finally, how about the appeal of a totally relaxed face and body – and the inevitable smile?

8. Finally… Feed Your Primal Self

I’m talking about more than your primal with a lowercase “p” appetite here. I mean your more inclusive, nuanced Primal (as in PB[20]) self. As I’ve said many a time, living Primally isn’t an exercise in asceticism[21] or deprivation. It’s about knowing and inhabiting your physical self more appreciatively, more pleasurably as well as responsibly. Sex isn’t just a procreative act. (Even in Grok’s day it served many more purposes than that.) Though technically unnecessary, it’s far from some isolated, tangentially relevant act. The desire and delight of sex is unique. It’s not an interchangeable element of our human experience. The shared intimacy and individual rapture teaches us, reveals to us, unfolds layers of our humanity, and lays bare a sensitivity and vulnerability, a vigor and power otherwise unknown to us. Even in its absence, sex helps define who we are and how we connect with life.

Not surprisingly, our sexual enjoyment extends far beyond the immediate physical crescendo. It has significance in our broader fulfillment. A cross-national study (PDF[22]) revealed that both men’s and women’s sense of sexual well-being significantly correlated with their general life satisfaction.

When it comes to garnering all the good health benefits of sex, a lot of readers ask about frequency. As I mentioned in last week’s fitness post, your start racking up the health gains at once a week, but the composite of research suggests that two to three times will maximize overall advantages. Needless to say, it’s well worth working into the calendar.

Okay, the floor is officially open to discussion. I’ll be interested to see what comes of today’s post and its suggestions… Thanks for reading, and I hope you were inspired today. Have a great day (or night, as the case may be), everybody.